Electric motor for shavers and the like



8, 1953 I. JEPSON 2,662,194

ELECTRIC MOTOR FOR SHAVERS AND THE LIKE Filed Oct. 51, 1947 3 Sheets-Sheet 1 IN VEN TOR.

ATTYs.

Dec. 8, 1953 l. JEPSON ELECTRIC MOTOR FOR SHAVERS AND THE. LIKE 3 Sheets sheet 2 Filed Oct. 31, 1947 Z N VEN TOR. Y

C /MM Y ATTYS.

Dec. 8, 1953 l. JEFSON ELECTRIC MOTOR FOR SHAVERS AND THE LIKE 5 Sheets-Sheet 3 Filed Oct. 51, 1947 INVENTOR.

Patented Dec. 8, 1953 ELEGTRIU MOTOR FOR SHAVERS AND THE LIKE Ever Jons n. Oak ark signo to Sunbe m mmot on Ghic q 111 a c or tion of Illinois Ap lication Octobe 31, 4 r al N team 6 Claims. (01. 310-50) This ent on e a s' o l ctric. moto s and m r i ular to motors i th typ use 111 electric sha ers s al hand P-Q r s and the like.

Hcr to re, conve t onal universal el ctric 1cm or o e ratin ontemp ated h r n ave b en generally circular in cross section; consequently, accede. a snug fit n externa in of m n mum mater h a sed n an electric shave the casin was a s en s circ la n shape- However, circular shaped casings have not in e er l be entir l satisfac ory or l t i s rs and th ke Th s. is d to reasons, am n the s o t e difiicultv i ovi g a n v rsa motor distin uish d fr m an m uls tre mo or havin suf c ent. P w r o a cas si e mal enou h to he on eni nt y h n e hand an to the tendency of t casing to roll off a su port n ur ace such a a sh lf o tabl and ma ch m -to unit A prima y obje of t e in ent on s he e. o provide an imn ved el ctr c mo o of the un ve sal. ommutator. se es w und ty as san u shed. rom im se t pe moto s. av ng s h ov co st uction cha act s cs as o make it suitable or operatin a. han imp em uh s n e ectric shav h us d not s pe as ng which. m y be. conve ient c n th han Auothsr b ec is to con truct a motor of h bove cha acte hich is small, an compa wh s mechani ll s ron hich be ead- 11 ass mb ed so t at the omponent parts a positively and accurately positioned and which b man actured a rela i el inexpensive noth r obje t is. to. provide a m tor of h above character with an improved f eld assembly construction that can be quickly and easily assembled with a minimum of effort.

nother o icc s th pr s o n a. motor of the above character having a field structure with a novel construction for fi ld coil $990k that s y he manu actur the o and faci i tates assembly of the spools on the laminated field structure.

Another object is the provision in a motor cirsuit of novel means for effecting an electrical connection between a brush holder assembly and the motor circuit that facilitates maintenance, that is easy to manufacture, that can be easily assembled.

Another object is to provide a novel means for connectin the motor with an external source of power that assures a positive electrical connection under all conditions of use.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accommov n w ng h h- Figure 1 is a side view of an electric razor having a cutaway portion showing a section of a motor embodying my invention;

Figure 2 is an end view of the electric razor with a cutaway portion;

Figure 3 is an elevational view similar to Figure 1;

Fi ure l is an end view of the field Stru t r before assembly of the motor;

F u e 5 is a plan ie of Figur 4;

Fi ure. 6 is an enlar ed fragm ta y ec o view showing details of construction of the field struct re;

Figure 7 is a sectional View taken substantially alo the l n 7?] of Fi u e Figure 3 is a perspective view of parts forming a fie d oil sp l;

Fi ure 9 is a cutaway s ctional view showin h ow r erm n l Figure 10. is a cutaway sectional view of an attac me t plus or se ith the power termi als shown in F gure 9;

i u e l1. shows he attachment plug connected to the power terminals;

Figure 12 is, a, diagrammatic view illustrating t no el r lationship be en t e m tor a d e sha er a a unit;

Figure 13 is a, sectional view taken substantially a on he l ne l3-l3 of Fi ure 1; and

Figu e ,4 is a diagr mmatic v ew illustrating the flux d stribution in h motor- R ferrin now to the drawings, the invention is shown embodied in a small compact motor 2! for user 1t e ectric shaver 2.2 of th typ used n shaving beards and the like. It is to be under? stood that the motor, can be used as the motivating power in any small power tool and that the e Of the m tor in th shaver 22 is by way f illustration only. The motor includes a. field u ure .3 omp sed of a plur ty f pi c s cured. o eth to o m a unitary s ructure of generally elongat d r ctangular shaped cross sec tion encircling the armature 2,4. The latter is supported by a shaft 26 suitably journaled in selfalining bearings 21 and 28 supported in bearing block supports 29 and 31 secured in a suitable manner to opposite ends respectively of the field structure 23.

One phase of my invention is concerned with forming a laminated field structure for small power motors such that the structure can be constructed with a minimum number 01' different parts and at the same time can be quickly and easily assembled in a rigid mechanically strong relation. For this purpose the field structure 23 comprises two parts 32 and 33 (see Figs. 4 and 5) abutting each other along spaced edge portions shaped to provide an interlocking fit and means for securing the respective parts 32 and 33 in an assembled relation to form a unitary field structure. Each of the parts 32 and 33 is identical and comprises a plurality of stampings 34 secured in side by side relation to form the laminated field structure. The stampings 34 as best seen in Fig. 4 are generally U-shaped and comprise a central portion 36 having arms 31 and 38 integral therewith extending outwardly from the central portion 36 in spaced relation. Preferably the outer portion of the arms 31 and 38 is formed so that when the respective parts 32 and 33 are assembled a suitable opening 39 is formed in the field structure for the reception of the armature 24. It is to be understood that the dimensions of the opening 39 in the structure are dependent on the rating of the motor, the air gap between the armature 24 and the field structure 23, and the like, all of which must be taken into consideration in the construction of a motor in accordance with practice well known in the art. The arms 3! and 38 are of such length that space is provided between the opening 39 for the armature 24 and the central portion 36 of the stampings 34 for the reception of a field coil 4| utilized for energizing the field structure during operation of the motor.

At its extreme outer end each arm 37 is formed with a projection 42. arm 38 is formed with a recess 43 shaped to receive a projection 42 of the same shape as the projection formed on the arm 31. In assembling the parts 32 and 33 the metal stampings 34 are preferably positioned so that the arms 31 with the projections 42 are alined and the arms 38 with the recesses 43 are alined. While any suitable means can be utilized for securing the respective laminations 34 of each part 32 and 33 in a tightly assembled relation, I prefer to stack the laminations 34 in a side by side relation and pass two spaced studs 44 through openings 45 formed in the laminations and provide abutments 41 and 48 on the elongated studs 44 that engage opposite ends of the laminated structure 23. It is to be understood that the spaced openings 46 through which the studs project are substantially the same dimensions as the studs and may be formed in the respective laminations during their forming process. Preferably the openings 46 are formed adjacent the interconnection between the arms 31 and 38 and the central portion 36 which. is of relatively large cross section to insure that the flux density in the magnetic circuit is not unduly increased. To simplify manufacturing, the studs 44 are preferably preformed with an annular shoulder which forms the abutment 4! at one end. When the desired number of laminations 34 are in a stacked relation the laminations are placed under pressure and a portion of each stud adjacent the opposite end is deformed to form the abutment 48 that engages the opposite end of the stacked lamina tions 23. This construction assures that the laminations 34 on each part 32 and 33 are held in a rigid tightly assembled relation at all times and under all service conditions.

The respective parts 32 and 33 may be secured together in any suitable manner to form a unitary field structure 23. I prefer to utilize links 49 In a similar manner each at opposite ends of the field structure 23. The links are formed with spaced apertures 5| for receiving the studs 44 passing through each respective part 32 and 33. Each link thus interconnects two studs 44. As shown in Figure 4 one link 49 connects the upper studs 44 together and one link 49 connects the lower studs 44 together. The links 49 are secured in a tightly assembled relation with the field structure 23 by nuts 52 threaded on the studs 44. As best shown in Figure 6 each of the links 49 is formed with a counterbore 50 on one side shaped to receive the respective abutments 41 and 48 formed on the studs 44 with a clearance fit and thereby permit the links 49 to abut against the end laminations 34 of the field structure 23.

Another phase of my invention is directed to an improved construction of a spool 53 for the field coils 4! that facilitates assembly of the respective components of the motor particularly where the laminations 34, and the field structure 23 are of the shape hereinbefore described. Thus it contemplates a spool 53 formed in two separable identical parts 54 each having spaced abutting edge portions 56 and 51 which when joined together interlock to form a unitary spool 53 having smooth external surfaces encircling the field structure 23. Preferably the respective parts 54 are formed from suitable insulating material. As best seen in Figure 8 each part 54 comprises a central portion 58 to which is integrally connected the edge portions 56 and 51 at opposite ends thereof. Each part 54 is generally of a U-shaped cross section having spaced ribs 59 integral with and projecting outwardly along opposite sides of the central portion 58 and the edge portions 56 and 51 respectively to form side members for the unitary spool 53. On the edge portion 51 the exterio surface of the edge por- '& tion and the inner portions of each rib 59 facing each other are fashioned so as to form a groove 6|, while on the edge portion 56 an exterior surface of each rib 59 and. the inner surface of the edge portion 56 are shaped to form a tongue 62 that will snugly fit in a groove 6| of the same shape as formed on the edge portion 51. The preshaping of the edges 56 and 51 and the associated ribs 59 is such that when the respective parts 54 are interlocked to form thespool 53 the thicknesses of the overlapping portions of the respective edges 56 and 51 and the overlapping portions of the ribs 59 are such that the thickness of the ribs and the sleeve of the spool are substantially uniform throu hout the periphery of th assembled spool. Thus, there will be no rough or sharp surfaces that will cause abrasion or damaging of the insulation on the field coils.

In assembling the spool 53 on the laminated structure 23 one part 54 of the spool. is positioned so as to straddle the alined central portions 36 of the assembled stampings and the other part is then positioned so it straddles the laminated structure from the opposite side thereof. The parts are alined so that the respective tongue 52 of each part 54 interfits with the groove 5| of the other part 54. To insure that the parts 54 remain in an assembled position a drop or two of acetone in case the spool is formed from plastic material or other solvent, as required, depending upon the material used, may be placed between the interlocking joints of the parts 54. The reaction between the solvent and the material of the spool is such as to eifect a tight J t 0f the respective parts 54. Preferably the overall dimensions of the spool 53 are such that the ribs 59 fit snugly against the arms 31 and 38 of the laminations 34-. The dimensions of the edge portions 56 and 51 and the central portion 58 should preferably be such that a snug fit is assured between the respective parts 54 and the laminated structure 23. It is to be understood that these dimensions depend on the motor rating and the like and are necessarily determined for each motor ratingv After the spool 54 is formed on the laminated structure 23-, the field coil wire is wound around the spool in its assembled position. The number of turns of wire for each field coil 4| of course is dependent upon the required field flux for each motor. This depends on the motor rating and can be readily determined by those skilled in the art for each individual motor rating. As soon as the required number of turns of wire are wound on the spool 53, a layer or so of insulating tape 63 is wrapped around the outer periphery of the wire to provide additional protection for the field coil 4|.

The bearing blocks 29 and 3| (see Fig. 3) are alined on opposite ends of the field structure 23 so that the armature 24 is accurately positioned in the opening 39 when the respective blocks 29 and 3| are secured to the field structure 23. To this end the respective blocks 29 and 3| are supported by the studs 44 utilized for securing the laminations 34 together and the nuts 52 for securing the links 49 to the assembly. Thus after the links 49 have been secured in position the respective nuts 52 are hollow milled to predetermined dimensions. The hollow milled portion of each nut 52 is accurately located with repect to the central axis of the opening 39 in the field structure 23. In a similar manner the bearing supports 29 andv 3| are formed with openings 94 shaped to snugly fit with the hollow milled por tion of the respective nuts 5'2. Thus when the bearing blocks 29 and 3| are pulled into position by nuts 66 in the assembly of the respective parts the bearings 2-1 and 23 (see Figures 1 and 2) supported in the respective blocks 2-9 and 3| are positively and accurately located so that the proper air gap exists between the armature 24 and the field structure 23;

The universal motor, operative on either alternating or direct current power, shown herein,- is a series motor of the com-mutating type. phase of my invention is concernedwith means for effecting a connection between brushes 67- and the motor circuit that facilitatesassembly and maintenance of the motor. For this purpose I utilize tubular shaped brush holders 68 (see Figure l-) shaped to hold the brushes 6'! and provide a removable cap 89, electrically connected in the motor circuit, shaped to fit over the end of the tubular members 68 to efiect a connection between the brush holder 68 and the motor circuit. As best seen in Figure .1; the motor shown herein utilizes two brushes 61. The brushes are received in the brush holders B8 herein iii-the form of sleeves 68 supported by the bearing block 3| so that one end of each sleeve is disposed adjacent a commutator 'H- and the other end projects through a wall 12 of a commutator chainber 13 formed in the bearing support 3|. The sleeves 98 are disposed on. opposite side's;v of the commutator H in a predetermined manner to obtain proper commutation. The outer end of each sleeve 68 is formed with a bead l4. ljhe cap 69 herein is formed with central portion is and depending resilient fingers 11 shaped tointeifit with th bead 14' so as to secure the cap One 69 to the end of the sleeve 6-8. A portion 18 of each cap 39 is shaped so that field leads 19 nah be secured thereto as by hooking an end of each lead 19 through an opening in the portion 18 and soldering the respective parts together. The pressure of each brush 8'! on the commutator is determined by a "spring 8| disposed between 'a shoulder 82 formed on the brush 6'! and the cap 99. This construction is advantageous in that the electrical connections and the brushes are readily accessible from the exterior of the motor for maintenance and service purposes; It also per mits the use of a relatively long spring 8| be= tween the brush 6! and the cap 69 which is do; sirable since the longer the spring the less variation there will be in brush pressures on the commutator as the brush 6? wears down in use; In some applications such as when the motor is us'e'd in a housing 89 which is formed by separable parts joined together as described in my co-pend= ing application; Serial No. 782,762, I utilize a strip of mica insulation 85 between the cap 69 and the housing 89'. This provides additional protection to the user of the motor against induced voltages in the motor and the like. I

Frequently in electric razors and power tools the construction of power terminals 83 and a plug 84 for connecting the respective terminals to a source of power is such that a positive connection between the respective" parts is not always assured. This is aggravated by the fact that in operation, particularly where the power terminals are located at a lower portion of the electric razor or tool when it is being used; the weight of the plug 84 and connected cord 86 tends to pull the plug 84' from engagement with the terminals 83. Accordingly my invention is concerned witha construction of the power ter' minals 83 and the plug 84 that positively assures an electrical connection between the respective parts under extreme service conditions. To this end the power terminals 83' are formed as elon-= gated prong members projecting through an insulating panel 81 (see Figs. 9, l0 and 11) slid ably disposd in spaced opposed grooves 88 formed on opposite sides of a recess 89 surrounding the terminals 83 at the extreme outer end of the bearing block 3|. As shown in Fig. 9 the recess 89 is disposed so that the terminals 83 are accessible from the exterior of the. motor housing 80 through an opening 92 formed there in. Field loads, 93 are connected to the terminals 83 through eyelets 94 embracing one end of the terminals 83. Herein the eyelet 94' is disposedbetween an insulating member 9| on one side of the insulating panel 81 anda peene'd end 91 of each terminal 83.- The peenedend 91 in effect forms a riveted connection which, coacting with ariannular shoulder 99 formed on the opposite side of the insulating panel 81, secures the ter mina'l's thereto in a rigid relation. The end of each terminal 83" projecting into. the recess 89 is formed with an axially extending slot 98 (see Fig 2) that: substantially bisects the. terminal.- With this construction each of the bisected parts of the terminal is slightly resilient and when in use with a. proper plug 84' will be stressed so that the outer ends of each bisected terminal are moved toward each other as shown in Fig. 11*v in a. stressed condition. Intermediate the ends of the terminals 83 the latter are deformed as by forming an annular bead 99 thereon. The plug 84 as best seen in Figs. 10 and 11 comprisestwo sleeve -like members |0| suitably mounted a pres'haped supportof suitable insulating material shaped to interfit in the opening 92 formed in the housing 80 and the recess 89. Each of the sleeve members IOI is formed with axially extending slots I02 that permit the sleeve parts to be spread apart under tension when the prongs 83 are inserted in the ends of the sleeve IOI. Preferably the sleeve ml is deformed as by forming an annular groove I03 at an intermediate portion thereof which when the sleeves IOI engage the prongs 83 in an operative relation receives the bead 99 formed on the prongs. The opposite end of each sleeve member IOI is shaped to receive the end I04 of a cable 86 adapted for connection to a power source. To assure a positive electrical connection between the sleeves IN and the ends of the cable I04, the end I06 of each sleeve IOI may be crimped as shown in Fig. 10.

In some motor applications the external movement and the end play of the armature 24 and associated shaft 26 must be maintained within extremely close tolerances to insure optimum operation. A construction for minimizing the end play of the armature 24 when the motor is used for driving an electric razor 22 is shown in I09 is disposed between the collar I01 and a t sleeve member III of the self-alining bearing 21. A second washer H2 is disposed between the opposite end of the sleeve member III and a shoulder II3 formed on an eccentric shaft II4 rigidly mounted on the shaft 26. The washers I09 and H2 are selectively chosen during assembly 0f the motor so that only washers of the 1 26 and engages the drive bracket II! of the elec tric razor 22 for driving the cutter blade thereof, not shown. The eccentric H6 is preferably in sulated from the armature 24 so that induced voltages in the shaft 26 are prevented from passing to the housing 80 and a comb IIB mounted at one end of the housing. As shown, a washer IIS (see Figures 1 and 2) of insulating material is disposed on a shoulder I2I formed on the eccentric shaft I I4. A second washer I22 of smaller diameter overlies the washer H9. The outer periphery of the washer I22 is preferably of an out-of-round preshape. A steel washer I23 supporting the eccentric H6 is provided with an opening of the same shape as the outer periphery of the washer I 22 so that the washer I22 is snugly received in the opening in the washer I23 when the parts are assembled as shown in Fig. 2. Preferably the washers I22 and I23 are of substantially the same thickness. A washer I24 is mounted to overlie both the insulating washer I22 and the eccentric washer I24. A washer I26 is mounted on the outer end of the eccentric shaft H4 and the latter is peened over to secure the washer I26 on the shaft II 4 and thereby retain the respective parts in a tightly assembled relation.

Suitable provision is made for oiling the motor bearings from the exterior of the housing 60 in which the motor is supported. For this purpose passageways l2I formed in bosses I28 on the interior of the housing 83 are positioned to form a continuation of the passageways I29 in communication with the bearings 26 and 2'! and extending through the bearing blocks 39 and 29 respectively. To facilitate alinement of the passageways each boss I2I is shaped to interfit in a recess I32 at one end of the passageway I29 formed in the respective bearing block. The recesses are somewhat larger than the bosses so as to allow for tolerances in manufacture. To pre-- vent leakage of oil from the passageways to the field structure a gasket I33 is disposed between a shoulder I34 formed on the boss and each respective bearing block.

Referring now more particularly to that phase of my invention dealing with the shape of the motor and the casing to provide the desired flat configuration together with motor characteristics for power and efficiency in operating a shaver of the oscillating cutter type, or for similar work, reference is made to Figures 12, 13, and 14. The motor is of such external configuration, consistent with performance requirements, that it can be readily disposed in a rectangular shaped casing having a chamber I 40 with a generally rectangular cross section, being of the largest dimensions at its central portion and tapering on each side thereof towards the ends of the casing, as shown in Figure 12. This is accomplished by constructing the field structure in two U-shaped parts which when assembled together in matching relation form a unitary field structure having a generally rectangular cross section as hereinbefore described. Flux for the motor is supplied by two coils, one being disposed on each of the shorter sides of the rectangular field structure. This construction in effect provides two separate fields supplying the total flux required for efficient operation of the motor, as shown in Figure 14. Thus the flux produced by the coil mounted on the right side of the structure follows the path formed by the central portion 36, the leg 37, the pole face I4 I, herein formed by the arcuate shaped outer end of the leg 31, an air gap I42 through the armature 24, an air gap I43, a pole face I44 herein formed by the arcuate shaped outer end of the leg 38 and thence through the leg 38 to the central portion 3-5. In a similar fashion the flux produced by the coil mounted on the left side of the structure shown in the Figure 14 follows the path formed by the central portion 36, the leg 38, pole face I45, an air gap I46 through the armature 24, an air gap I41, the pole face I48, back through the leg 31 to the central portion 36 with the coils wound so that the flux follows the paths as described above. It will be seen that the pole faces MI and I45 are of the same polarity and the pole faces I44 and I48 will be of the same polarity. It is to be understood that so disposing the field coils on the field structure the thickness of the field structure is maintained at a minimum whereas the overall width of the field structure is in creased to some extent by the field coils. This latter is desirable in providing a mounting for the brush assembly. To obtain longer life of brushes, consistent with performance, it is necessary to provide a brush holder that permits considerable automatic adjustment of the brushes. As fully described hereinbefore my brush holders are formed by tubular members 68 inserted in the bearing block 3| on opposite sides of the armature. By disposing these tubular members in the same plane of the field structure as the coils I provide a brush holder with a spring suificiently long that it has the proper characteristics to assure constant brush pressure as the brush wears away due to engagement by the armature. It will also be noted that the armature positioned on the side of the motor remote from the head. Heretofore, in constructions of this type the armature was mounted on the shaft adjacent to the driving end of the shaft. The eccentricity developed by the shaft in such constructions caused wearing of the bearings, affected the brush engagement with the armature to such an extent that there was a considerable amount of undesired sparking. By disposing the armature as described above, the eirect of the eccentricity of the shaft due to wear of the bearing adjacent to the driving end thereof is minimized and consequently undesired sparking of the brushes is minimized.

It is to be understood that the field structure together with the insulation bloclgs is a selfscontained unit and that the motor can be tested as such before it has been assembled in the housing 80. Any suitable means may be utilized for mounting the motor in its housing 80. One such construction is fully described in my cospending application, Serial No. 782,762, filed October 29, 1947. It is to be understood that the motor mounting in each instance will depend on the application and the shape of the tool or implement in which it is to be used. It is also to be understood that any of the parts such as the shape of the bearing blocks 29 and 3| can be readily modified to suit any individual a-pplicae tion.

While I have shown one embodiment of my invention it will be understood that I do not wish to be limited thereto since many modifications may be made, and I therefore contemplate by the appended claims to cover such modifications as fall within the true spirit and scope of my invention.

I claim:

1. A motor unit having a hand grip casing of substantial length in relation to its width and thickness, an armature disposed lengthwise within said casing, a field structure within said casing surrounding the armature having a substantially rectangular cross section conforming with the width and thickness of the casing, insulation supporting blocks on opposite ends of said field structure and clamped directly thereto independently of said casing, an implement head having a substantially rectangular base section mounted on one of the supporting blocks at the outer end thereof, a current supply connector of substantially rectangular cross section at the end of the casing opposite from said implement head, the casing having an exterior configuration generated by tying the four corners of the implement head cross section at one end with the four corners of the field cross section at the center and with the four corners of the connector cross section at the opposite end to provide a fiat hand grip casing.

2. A motor unit having a hand grip casing provided at one end with an implement drive and at the opposite end with a current supply, a universal motor within the medial portion of the casing having an armature extending lengthwise within the casing and having a commutator at its end adjacent to the current supply end, a generally rectangular shaped field structure having long and short sides, field coils encircling said short sides, the armature being disposed in said field structure, insulation supports secured to said field structure at opposite ends thereof independently of said casing for rotatably supporting the armature, one of said supports enclosing said commutator, a brush holder assembly mounted on each side of said latter support, a brush disposed in each of said holders to engage said commutator on diametrically opposite sides, said holder being disposed in a plane normal to said short sides of the field structure, the overall dimensions in a plane through the brush holder assemblies being less than the overall dimensions through a cross section plane of the field structure including the field coils.

3. A motor comprising an armature having a shaft, a two part laminated field structure comprising laminations having a central portion and spaced arms projecting outwardly therefrom, one of said arms having a recess formed thereon and the other of said arms having a projection formed thereon shaped to interfit with a recess of the same shape as formed on the first arm, the laminations of each part being positioned so that the projections are alined on one side of the part and the recesses are alined on the opposite side of the part, said parts being arranged so that the alined projections of one part interfit with the alined recesses in the other part, said laminations being shaped so that in the assembled position of the parts an opening is formed for said armature, field coils encircling said field structure at spaced positions for energizing said field structure, bearings for supporting said shaft, bearing supports disposed on opposite ends of said field s'truc ture, and means for clamping the bearing supports to the field structure in a tightly assembled relation independently of any other structure associated with said motor whereby to positively aline said armature with respect to said field structure.

4. A motor comprising an armature having a shaft, a two part laminated field structure comprising laminations having a central portion and spaced arms projecting outwardly therefrom, one of said arms having a recess formed thereon and the other of said arms having a projection formed thereon shaped to interfit with a recess of the same shape as formed in the first arm, the laminations of each part being positioned so that the projections are alined on one side of the part and the recesses are alined on the opposite side of the part, said parts being arranged so that the alined projections of one part interfit with the alined recesses in the other part, said parts being shaped to form a central opening for said armature, opposed spaced links at opposite ends of said parts holding said parts in position to form a unitary structure, field coils encircling said field structure at spaced positions for energizing said field structure, bearings for supporting said shaft, bearing supports disposed on opposite ends of said field structure, and means independently of any other structure of said motor for clamping the bearing supports to the field structure in a tightly assembled relation.

5. An electrical insulating spool of the type used for field coils embracing a yoke or the like, comprising two separable pieces, each of said pieces comprising a member having a central portion and outwardly projecting edge portions, said portions having spaced ribs formed thereon along opposite sides, one of said edge portions and the associated ribs being fashioned to form a groove and the other of said edge portions and the associated ribs being fashioned to form a tongue shaped to fit snugly in a groove of the shape formed in the first edge portion, said members being so dimensioned that with the tongue of one member interfitting with the groove of the other and the tongue of the other interfitting with the groove of the first, they form a spool of predetermined shape, shaped to encircle the yoke and having a smooth exterior surface upon which wire may be wound to form a field coil.

6. In a field assembly, a two part separable field structure composed of a plurality of laminations comprising a central portion and outwardly extending arms integral with opposite ends of said central portion, one of said arms being formed with a recess and the other of said groove formed thereon and an opposite edge portion shaped to fit snugly in a groove of the same shape as formed on the first edge portion, said members when joined together forming a spool having a smooth exterior surface for the reception of wire for field coils, and links disposed on opposite ends of said parts for securing the parts together to form a unitary structure so that the projections of each part interfit with the recess of the other part in the assembled structure.

IVAR JEPSON.

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